Blasting cartridges



Oct. 12, `1965 H. c. FOSTER 3,211,095

BLASTING CARTRIDGES Original Filed Aug. 2l, 1959 2 ShEGS-Sheet l FIG. l

iN VEN TOR.

HARRY CLARK FOSTER A T TOP/VE Y y Oct. l2, 1965 H. c. FOSTER 3,211,095

BLASTING' CARTRIDGES Original Filed Aug. 21, 1959 2 Sheets-Sheet 2 FIGEBl5) (59 f8 5H f5 INVENTOR.

HARRY CLARK FOSTER BYWWJ W A TTORNEY United States Patent O 3,211,095BLASTING CARTRiDGES Harry Clark Foster, Rosewood Heights, East Alton,Ill.,

assignor, by mesne assignments, to Commercial Solvents Corporation, acorporation of Maryland Original application Aug. 21, 1959, Ser. No.835,267. Divided and this application Nov. 13, 1962, Ser. No.

. this type of blasting cartridges consisted essentially of acylindrical gas containing cartridge having venting means. Thecartridges were charged with gas under considerable pressure, sealed andthen conveyed to the face to be worked. The compressed gas within thesecartridges was released by elaborate remote control means. More recently, the practice has been to place an uncharged cartridge in thebore hole and pump gas through a suitable conduit into the cartridge insitu. Conventionally, these cartridges are formed of high strengthmaterials and are provided with a relatively weak member which shears orruptures so as to liberate the gas from the cartridge body. Since theamount of pressure that can be built up in the cartridge body isdependent upon the strength of the expendable member, the quantity ofenergy developed by the liberation of the gas can be controlled withinrelatively close limits. Such cartridges are generally satisfactory buthave one serious inherent drawback. After each shot, the discharge endof the Cartridge must be dismantled to remove the expendable portionwhich has ruptured or sheared and to replace it with a new one.

This shortcoming has been well recognized and has led to a concertedeffort for the development of automatic shells. While many so-calledautomatic shells have been presented, they have met with only a modicumof success. The previous types of automatic cartridges are operable, butthey are very heavy, complex and unreliable. Although the expendableportions of the shell have been eliminated, this elimination haslintroduced new and more serious problems. Normally, the known automaticshells rely upon a series of two or more control or pilot valves toinitiate the main release valve. Such complexity of design leads tocartridges that are difficult to control and exceedingly difficult todischarge at a desired predetermined pressure. In addition, the greatnumber of moving parts in the automatic shells prior to the advent ofthe present invention has confronted the industry with a formidablesealing problem.

Therefore, it is an object of this invention to provide new and improvedautomatic or semi-automatic material breaking devices utilizingcompressed gas. A further object is to provide a device of thischaracter having novel gas release means. Another object of thisinvention is to provide a simplied automatic or semi-automatic shellovercoming the disadvantages of the prior art.

The manner in which these and other obiects are achieved will beapparent from the following specification together with the drawing inwhich:

FIGURE l is a longitudinal sectional view of a device illustrating apreferred embodiment of the present invention;

3,211,05 atented Oct. 12, 1965 ice FIGURE 2 is a longitudinal sectionalview of the device of FIGURE l in an open position;

FIGURE 3 is a longitudinal sectional view of a device illustratinganother embodiment of the present invention; and

FIGURE 4 is a longitudinal sectional view of a modification of thedevice shown in FIGURE 3.

The same numbers are used throughout the drawing to identify similarcomponents.

Referring to FIGURE l which illustrates a preferred embodiment of theinvention, an elongated tubular body formed of metal of a strength tocontain gas under high pressures, for example, pressures from 6,000 to20,000 pounds per square inch, is indicated generally at 1. Only aportion of this tubular body, which may be of the order of 50 inches ormore in length, is shown. Suitable means, such as a compressed air line2, are provided at one end of the cartridge body for introducingcompressed gas into it. The outer diameter of the body is such that itmay be set freely within a bore drilled in the face of the material,such as coal, to be mined and broken down. The end of the body remotefrom the gas inlet is closed with an end cap 3. The body and the end capare screw threadedly attached as shown at d. The seal between thetubular body and the end cap is completed by an annular resilientsealing means 5. The interior of the cylindrical body is divided into amain chamber 6 and a secondary chamber 7 by main valve 8, which isslidable therebetween.

That portion of the main chamber in proximity to the main Valve 8 is ofa slightly smaller diameter than the remainder of the main chamber dueto the presence of constriction 9, one end of which forms a conicalvalve seat 10. As particularly well shown in FIGURE 2, that portion ofthe constriction between the valve seat 1t) and the wall 11 issubstantially perpendicular to the interior wall. This configuration ofthe face of the constriction and beveled surface 12 on the main valvecooperate to form an annular sealed chamber 13 between the valve and theconstriction. The main valve 3 is normally urged into seating positionwith the valve seat 10 by helical spring 14 in secondary chamber '7. Anysuitable means can be employed to replace or augment this action of thespring 14.

Main valve 8 carries tubular fixture 15 in a central bore 16. Thefixture is screw threadedly attached to the main valve as indicated at17 and the seal between these two members is completed by resilientsealing means such as an O-ring 18. A control piston 19 provided with anoriiice 20 therethrough is slidable within fixture 15 and main valve 8.The piston is slidably sealed to these members by Orings 21 and 22.Helical spring 23, positioned about the control piston, normally urgesit in a direction toward the main chamber 6. The space 2d about theexternal periphery of the control piston 19 is vented to the atmospherethrough passageway or vent 25. Valve member 26 is screw threadedlyafiixed to the main valve 8, as shown at 27, and secured in position bylock nut 23. It will be noted that orifice 20 in the control piston 19provides a communication between main chambers 6 and secondary chamber 7through area 29 at the base of the piston and a plurality of passageways30. A sliding seal between end cap 3 and main valve S is provided by O-ring 31.

`By reference to the drawing, it will be noted that the effective tareaof the main valve `8 defining one end of secondary chamber 7 is greaterthan the effective area of :the main valve forming an end 4of mainchamber 6. Thus, when the gas pressure is equal on both sides of themain valve, the Valve is urged into sealing position with valve seat 10and spans ports 32. Likewise, the effective area of control piston 19subject to the gas pressure in main chamber 6 is greater th-an theeffective area of the control piston exposed to the 4gas pressure insecondary chamber 7. Thus, when the equalizing pressures in chambers 6and 7 are increased, control piston 19 is urged toward seatingarrangement with valve member 26, in opposition to the action of helicalspring 23.

yIn operation, compressed air or other suitable gas is introduced intomain 4chamber 6` through gas inlet 2. The air passes through orificeZtl, larea 29 and passageways 3ft into the secondary chamber. Thus, thepressure on either Iside of the main valve t; is substantiallyequalized. Hotwever, bec-ause of the greater effective cross sectionalarea of valve 8 in .the secondary chamber than in the main chamber, thevalve is urged into sealing relationship with valve seat 10 andmaintains discharge ports 32 in a closed position. 'Since -this action,due to the differential eff-ective area of the valve increases withincreased pressure, the seal between the main valve tt and valve seat.itl increases progressively `as pressure builds up within thecartridge.

As the gas pressure is increased within the cartridge, control piston.19 is forced toward valve member 26. This action continues until theorifice is completely closed at a pressure that can be predetermined bythe ratio of the differential areas of piston 1% and also by the forceexerted by helical spring y23. 'In this way, secondary chamber 7 iseffectively sealed from main chamber 6 to a predetermined pressure lessthan the discharge pressure of the cartridge.

After the secondary chamber 7 is thus sealed by cooperation of controlpiston 19 and valve member 26, the pressure in the main chamber and onthe smaller effective cross sectional area of the main valve increasesuntil the [force overcomes that of the lower pressure on the larger areaof the control valve in the secondary chamber. At this point, the mainvalve is unseated. As soon as the main valve unseats slightly, thepressure in the main chamber is lapplied to that portion 12 of the valvein the .annular sealed chamber 13. Thus, the effective crosssectionalarea of the valve in the main chamber is suddenly increased and the mainvalve 8 is forced back exposing lateral ports 32. The charge ofcompressed gas in main chamber 6 is thus completely `and instantaneouslyreleased to the surrounding work face which is to be broken down.

The control piston y19 opens practically simultaneously with anyappreciable movement of the main valve 8. This opening is due in part tocompression within secondary chamber 7 and also to `a pressure drop inthe main chamber I6. When the charge of air leaves rnfain chamber 6reducing the pressure therein, main valve 8 is returned to its originalposition -by helical spring y14 or any other suitable means.

In the embodiments shown in FIGURES 3 and 4, the configuration of thechambers and the main valve member is substantially the lsame as thatillustrated in FIGURE 1. These embodiments differ from that of FIGURE 1only in the employment of la somewhat different type of control valvemeans carried Iby `rnain valve 8. In these embodiments, permanentcommunication Ibetween main chamber 6 and secondary chamber 7 isprovided by one or more pass-ageways 33 through the main valve 8. Thus,the pressures in these chambers are maintained substantially equalthroughout the operation of the cartridge. The main valve S is providedVwith an orice 34- which communicates with the annular sealed chamber 13through one -or more passageways 36. The orifice 34 is normally closedby a self-centering ball type valve 35 which is urged into sealingposition with the orifice by helical spring 37 .transmitting its -forcethrough valve seat rnernber 38. The cont-rol valve member-s rareadjustably maintained in position by set screw 39 and fixture 40 whichare screw threadedly connected to the main vealve and ysealed theretowit-h O-rings 41 :and 42. Any pressure build up in the area about thespring and under the valve seat member which would prevent properfunctioning of the control Valve is avoided by vent 43, shown in FIG-UR/E 4, which communicates with the atmosphere through port 3-2.

In the operation of the embodiment 4of FIGURES 3 and 4, the Apressure onboth sides of the main valve 8 is maintained substantially equal becauseof passageways 33 therethrough. However, the torce on the side of thevalve facing the secondary chamber 7 is greater than that on the sidefacing the main c-hamber because the valve has a `greater effectivecross sectional area in the secondary chamber than in the main chamber.Thus, the seal between the valve and the valve seat `10 increases aspressure within the cartridge builds up. Thus, the escape of gas priorto reaching the discharge pressure of the cartridge is effectivelyeliminated. When the discharge pressure is approached, the pressure inthe main chamber acting on yball valve 35 forces it downward toward thesecondary chamber 7. In this way, the pressure in the main chamber istransmitted to the annular sealed chamber 13 through orifice 34 andpassageways 36. Since the effective cross-sectional area of the mainvalve exposed to the pressure in the main chamber is thus abruptlyincreased to a value greater than the cross-sectional area of the valvein the secondary chamber, the main valve is suddenly forced away fromthe lateral ports 32 and the charge of compressed gas in the mainchamber f6 is effectively and substantially instantaneously released tot-he surrounding work surface. After 4the cartridge has been discharged,the main valve is returned to its original position by helical spring 14and the cartridge is again in condition for charging.

The embodiment shown in FIGURE 4 is substantially the same as thatillustrated in FIGURE 3 but differs therefrom in two main respects. Thatportion of the main valve S in contact with the constriction 9 isextended so as to form a sliding fit, as indicated at 44 with theinternal surface of the constriction. The seal between the main valveand the constriction in this embodiment is completed by an annularresilient sealing means, Such as an O-ring 45. Also, helical spring 14has been replaced with a manual reset plunger 46 slidable in the end cap3 and sealed thereto by means of O-ring 47. Thus, in accordance withthis embodiment, the cartridge is semi-automatic instead of automatic,and the seal between the main valve is and the main chamber 6 is of thesliding type rather than the conical seat type. While thesemodifications have been described with particular reference to FGURES 3and 4, it will be readily appreciated that they can be readilyincorporated into the embodiment of FIG- URE l. Also, the helical springand reset plunger can be employed in the same cartridge or can bereplaced by other equivalent means which will return the main valve intoa closed position.

Although the invention has been described in considerable detail in theforegoing for the purposes of illustration, it is to be understood thatsuch detail is solely for that purpose and that many modifications can'be made without departing from the spirit and scope of the invention.

What is claimed is:

1. A reusable blasting cartridge comprising a substantially -cylindricalhousing having a main chamber for containing a charge of compressed gas,means at one end for introducing gas under pressure, an enclosedsecondary chamber, a lateral outlet intermediate the ends of thehousing, a pressure responsive main valve having a body slidable 1n saidhousing between the main chamber and the secondary chamber and normallypositioned to span and seal said outlet, a passageway through the valvebody interconnecting the chambers, an internal annular restricttion 1nthe housing adjacent the lateral outlet .and positioned between theoutlet and the gas inlet, said valve body having a greater diameter thanthe internal diameter of the constriction and a narrowed forward portionadapted for seating on the restriction in said main chamber, saidnarrowed forward portion forming with said housing an annular obturatedchamber 4between the restriction and the main valve body, the narrowedforward porti-on of the valve body facing the main chamber having aneffective area less than the effective area of the Valve body in thesecondary chamber, while the sum of the effective areas of the narrowedportion olf the valve body and that portion of the valve body Within theobturated annular chamber is greater than the effective area of thevalve body in the secondary chamber, a control valve within the mainvalve body, said control valve being solely responsive to pressurewithin the main chamber, a vent within the narrowed forward portion ofsaid main valve body extending between the main chamber and the annularsealed chamber normally closed by the control valve and means in thesecondary chamber for returning the main valve to a position spanningthe lateral outlet.

2. A cartridge comprising a substantially cylindrical housing having amain -chamber for containing a charge of compressed gas, inlet means atone end of said housing adapted to introduce gas under pressure to saidmain chamber, a lateral outlet intermediate the ends of said housing, aninternal annular constriction in said housing adjacent the outlet andpositioned between the outlet and the inlet means, a pressure responsivemain valve slidably mounted in said housing and normally positioned toseat on said constriction and to seal said outlet, an enclosed secondarychamber in said housing, said main valve having :a first end forming anend facing said main chamber including a rst portion of said mainchamber and a second end forming an end of said secondary chamber, asealed `annular chamber formed in said housing between said constrictionand a second portion of said first end of the main valve, said secondportion of the cross-sectional area of said rst end being normallyenclosed in said annular chamber lso that it is not affected by thepressure in said housing during charging of said cartridge, said rstportion of the cross-sectional area of said first end being exposed tothe charging pressure in said housing, the total cross-sectional area atsaid first end of said valve being greater than the totalcross-sectional area at said second end of said valve, said second endof said valve having a greater cross-sectional area exposed to thecharging pressure in the housing than said first portion of the rst endof said valve, a passageway in said main Valve for equalizing thepressure in Said main chamber and means including said secondarychamber, and control valve means mounted in said main valve operative toopen said sealed annular chamber to the charging pressure in the mainchamber at a predetermined discharge pressure and in said main chamberwhereby to expose said second portion to the pressure in `said mainchamber and open said lateral outlet.

3. A cartridge comprising a substantially cylindrical housing having amain chamber for containing a charge of compressed gas, inlet means atone end of said housing adapted for the introduction of gas underpressure to said main chamber, a lateral outlet intermediate the ends ofsaid housing, an internal annular constriction in said housing adjacentthe outlet and positioned between the outlet and the inlet means, apressure responsive main valve slidably mounted in said housing andnormally positioned to seat on said constriction and to seal saidoutlet, an enclosed secondary chamber in said housing, said rnain valvehaving a rst end forming an end of said main chamber and a second endforming an end of said secondary chamber, said rst end including anarrowed forward portion having a cross-sectional larea exposed to thepressure in said main chamber less than the cross sectional area of saidsecond end, a sealed annular chamber formed in said housing by saidconstriction and said narrowed forward portion, said first end includinga Isecond portion normally enclosed in said annular chamber and notatected -by the pressure in said housing during charging of -saidcartridge, the total cross-sectional area at said first end of saidvalve being greater than the total cross-sectional -area at said secondend of said valve, a iirst passageway in said main valve equalizing thepressure in said main chamber and said secondary chamber whereby saidsecond end of said main valve has a greater crosssectional area exposedto the pressure in the housing during charging of the cartridge thansaid rst end of said valve, a second passageway in said narrowed for-Ward portion of the main valve interconnecting said main chamber withsaid sealed annular chamber, spring biased control valve means mountedin said main valve and normally closing said second passageway, saidcontrol valve means being operative at a predetermined pressure withinsaid main chamber to open said second passageway to allow the chargingpressure of said main chamber to enter said sealed annular chamberthereby greatly increasing the area at said first end of said main valveeX- posed to the charging pressure in said housing.

4. The cartridge of claim 3 further including spring means in thesecondary chamber for normally constantly biasing the main valve to aposition -spanning the lateral outlet, said spring means exerting lesspressure on the main valve than is exerted on said control valve means.

5. The cartridge of claim 3 further including a manually slidableplunger arranged in said secondary chamber for returning the main valveto a position spanning the lateral outlet.

6. The cartridge of claim 3 wherein said main Valve has -a chambertherein for containing said spring biased control valve means andfurther including a third passageway in said main Valve adapted toconnect the portion of said last-mentioned chamber on the side 4of saidcontrol valve means opposite said second passageway with the atmosphere.

References Cited bythe Examiner UNITED STATES PATENTS 382,643 5/88 FOX137-490 591,013 10/97 Schreidt 137-490 2,420,370 5/47 Hamilton 137-4692,720,169 10/55 Smith 102-25 SAMUEL FEINBERG, Primary Examiner.

1. A REUSABLE BLASTING CARTRIDGE COMPRISING A SUBSTANTIALLY CYLINDRICALHOUSING HAVING A MAIN CHAMBER FOR CONTAINING A CHARGE OF COMPRESSED GAS,MEANS AT ONE END FOR INTRODUCING GAS UNDER PRESSURE, AN ENCLOSEDSECONDARY CHAMBER, A LATERAL OUTLET INTERMEDIATE THE ENDS OF THEHOUSING, A PRESSURE RESPONSIVE MAIN VALVE HAVING A BODY SLIDABLE IN SAIDHOUSING BETWEEN THE MAIN CHAMBER AND THE SECONDARY CHAMBER AND NORMALLYPOSITIONED TO SPAN AND SEAL SAID OUTLET, A PASSAGEWAY THROUGH THE VALVEBODY INTERCONNECTING THE CHAMBERS, AN INTERNAL ANNULAR RESTRICTTION INTHE HOUSING ADJACENT THE LATERAL OUTLET AND POSITIONED BETWEEN THEOUTLET AND THE GAS INLET, SAID VALVE BODY HAVING A GREATER DIAMETER THANTHE INTERNAL DIAMETER OF THE CONSTRICTION AND A NARROWED FORWARD PORTIONADAPTED FOR SEATING ON THE RESTRICTION IN SAID MAIN CHAMBER, SAIDNARROWED FORWARD PORTION FORMING WITH SAID HOUSING AN ANNULAR OBTURATEDCHAMBER BETWEEN THE RESTRICTION AND THE MAIN VALVE BODY, THE NARROWEDFORWARD PORTION OF THE VALVE BODY FACING THE MAIN CHAMBER HAVING ANEFFECTIVE AREA LESS THAN THE EFFECTIVE AREA OF THE VALVE BODY IN THESECONDARY CHAMBER, WHILE THE SUM OF THE EFFECTIVE AREAS OF THE NARROWEDPORTION OF THE VALVE BODY AND THAT PORTION OF THE VALVE BODY WITHIN THEOBTURATED ANNULAR CHAMBER IS GREATER THAN THE EFFECTIVE AREA OF THEVALVE BODY IN THE SECONDARY CHAMBER, A CONTROL VALVE WITHIN THE MAINVALVE BODY, SAID CONTROL VALVE BEING SOLELY RESPONSIVE TO PRESSUREWITHIN THE MAIN CHAMBER, A VENT WITHIN THE NARROWED FORWARD PORTION OFSAID MAIN VALVE BODY EXTENDING BETWEEN THE MAIN CHAMBER AND THE ANNULARSEALED CHAMBER NORMALLY CLOSED BY THE CONTROL VALVE AND MEANS IN THESECONDARY CHAMBER FOR RETURNING THE MAIN VALVE TO A POSITION SPANNINGTHE LATERAL OUTLET.